The present invention relates to mounting structure for the replaceable attachment of objectives to microscopes.
As a general rule, microscope objectives have a fine thread by which they are removably mounted to the turret of a microscope. For more than a century, this type of mounting has been used exclusively for microscope objectives since it well satisfies existing requirements, among other things, for an accurately centered seating of the objective. With a threaded attachment, the mounted angular position of the part which is threaded-in is not fixed so that, for example, legends on the objective housing frequently are no longer legible after threaded advance into the objective turret. Thus far, this disadvantage has always been tolerated, along with the relatively cumbersome process of threaded advance into (or retraction from) the fully mounted position.
In other fields of optics, for example photo-optics, it has long been known to attach objectives via a so-called bayonet mount to the involved camera. The bayonet mount permits rapid change of the objective and also assures that the objective is always locked in the same angular position so that, for example, actuating devices and scales for aperture, distance, etc., are always accessible to the user at the same angular location.
However, with respect to centering accuracy, much less stringent demands are made on the mounting of a camera objective than on the mounting of a microscope objective since, in a camera, the film plane lies directly behind the objective, and lateral offset of the image on film to be exposed is, as a rule, without deleterious effect. Bayonet attachments for interchangeable photographic objectives, therefore, have flat reference surfaces against which corresponding mating surfaces of the objective are pressed by spring means, in the course of making the bayonet engagement.
In microscopes, the objective is one of a plurality of optical elements whose axes must be accurately aligned with the axis of the objective if the quality of the microscopic image is not to be impaired. For this reason, it is not possible to provide microscope objectives with a locking bayonet mount as used for photo objectives.